From source: “I have now received e-mails from totally trustworthy sources within Iran that many Sepaah commanders [Sepaah is IRGC] have been arrested, because they are opposed to what is going on and in particular to the plan for tomorrow.

“This had been talked about for the past few days, but my source confirmed it.” end quote

Clarification for plans for tomorrow: “Apparently, the plan is to create chaos and bloody confrontation between Basij and Karroubi and Mousavi demonstrators, in order to justify hard crack down and have Khamenei announce the end of “soft” confrontation in the Friday prayers.”

Related rumor here. There’s corroborating evidence (albeit anecdotal) that some Guard members might refuse to participate in a crackdown, too, thereby necessitating the sort of purge described by TB. From the LA Times, via Michael Totten:

Perhaps more perilous for authorities is the possibility that some soldiers, security officials and Revolutionary Guardsmen might refuse orders to fire on protesters, creating a dangerous rift within the security apparatuses.

“I would never do it,” said Hossein, a 23-year-old member of the security forces who said he and many of his friends at the military base where he serves support the marchers. “Maybe someone would, but I would never fire on any of these people myself.”

Khamenei’s conducting the prayers tomorrow at Tehran University, where five students were reportedly killed in a Basij brownshirt assault on the dorms. Is that meant as a gesture of provocation or reconciliation? Maybe both: Presumably he’ll start off by paying lip service to what a tragedy it is that kids have died, then none-too-subtly warn that more people will inevitably die in the “confusion” if they don’t get off the streets post haste. Three things I can’t figure out, though. (1) If Khamenei’s preparing for a bloodletting, why would he want his face out in public at Friday prayers before it begins? All that does is drive home the fact that he’s complicit in it. (2) The Guardian Council’s still supposed to meet with all four presidential candidates on Saturday to talk about the vote. Is a crackdown tomorrow meant to keep that from happening or is the crackdown actually set for Saturday, after the meeting, which is bound to prove unsatisfactory to Mousavi? (3) If it’s true, and it probably is, that Rafsanjani is rounding up support from top mullahs in Qom for him and Mousavi, why haven’t we heard anything from them yet? Surely they’d want to come out in favor of the protesters before a crackdown begins, to throw the full weight of their authority against the Guard in hopes that they’ll back down in fear of damnation. As it is, if the last thing Iranians see before a Tehran Tiananmen is launched is Khamenei intoning about religion at Friday prayers, they’re apt to target the whole clerical system for reprisals. Good news for the west, not so good if you’re a mullah. Might want to speak up while you can.

Two vids from today’s monster rally as you ponder, one from CNN calling this possibly the largest protest in the history of the Islamic Republic and the other raw video of Mousavi’s appearance among the ecstatic crowd.

The moderate Iranian leader who says that he was robbed of victory in last week’s presidential election faces a fateful choice today: support the regime or be cast out.

Ayatollah Ali Khamenei, Iran’s Supreme Leader, has told Mir Hossein Mousavi to stand beside him as he uses Friday prayers at Tehran University to call for national unity. An army of Basiji — Islamic volunteer militiamen — is also expected to be bussed in to support the Supreme Leader.

The demand was made at a meeting this week with representatives of all three candidates who claim that the poll was rigged, and it puts Mr Mousavi on the spot…

It was unclear last night what he would do or even whether the protests would die away if he backed down.

Update:The Standard notes that Mousavi’s Twitter feed has a message out urging supporters not to go to prayers tomorrow, which presumably means he won’t be there either. In the unlikely event that they take his advice, that’ll reduce the odds of confrontation. But if he boycotts the event too, it’s a direct slap at Khamenei’s authority. Which means this isn’t Mousavi versus Ahmadinejad anymore, it’s Mousavi versus the whole regime.